//指定天数加1天
function dateAdd(startDate) {
  startDate = new Date(startDate);
  startDate = +startDate + 1000*60*60*24;
  startDate = new Date(startDate);
  var nextStartDate = startDate.getFullYear()+"-"+(startDate.getMonth()+1)+"-"+startDate.getDate();
  return nextStartDate;
}

//指定天数加N天
function   DateAdd(interval,number,date)
{
  /*
   *   功能:实现VBScript的DateAdd功能.
   *   参数:interval,字符串表达式，表示要添加的时间间隔.
   *   参数:number,数值表达式，表示要添加的时间间隔的个数.
   *   参数:date,时间对象.
   *   返回:新的时间对象.
   *   var   now   =   new   Date();
   *   var   newDate   =   DateAdd( "d ",5,now);
   *---------------   DateAdd(interval,number,date)   -----------------
   */
  switch(interval)
  {
    case   "y"   :   {
      date.setFullYear(date.getFullYear()+number);
      return   date;
      break;
    }
    case   "q"   :   {
      date.setMonth(date.getMonth()+number*3);
      return   date;
      break;
    }
    case   "m"   :   {
      date.setMonth(date.getMonth()+number);
      return   date;
      break;
    }
    case   "w"   :   {
      date.setDate(date.getDate()+number*7);
      return   date;
      break;
    }
    case   "d"   :   {
      date.setDate(date.getDate()+number);
      return   date;
      break;
    }
    case   "h"   :   {
      date.setHours(date.getHours()+number);
      return   date;
      break;
    }
    case   "m"   :   {
      date.setMinutes(date.getMinutes()+number);
      return   date;
      break;
    }
    case   "s"   :   {
      date.setSeconds(date.getSeconds()+number);
      return   date;
      break;
    }
    default :   {
      date.setDate(d.getDate()+number);
      return   date;
      break;
    }
  }
}

//var   now   =   new   Date();
////加五天.
//var   newDate   =   DateAdd( "d ",5,now);
//alert(newDate.toLocaleDateString());
////加两个月.
//newDate   =   DateAdd( "m ",2,now);
//alert(newDate.toLocaleDateString());
////加一年
//newDate   =   DateAdd( "y ",1,now);
//alert(newDate.toLocaleDateString());